Cardiac rehabilitation programs (CRP) reduce overall and cardiovascular mortality in patients recovering from acute coronary events or revascularization procedures. Modifiable coronary risk factors such as physical inactivity, overweight and high serum lipid levels also improve after CRPs. However, only 30% of patients currently enroll in CRPs and attrition may reach 60%. Barriers include older age, female gender, fear or dislike for the type of exercise training proposed in CRPs, lack of social support, depression and distance from CRP center. Clearly, there is a need to develop programs tailored to the characteristics and needs of those who do not attend presently available programs. Tai Chi, a mind-body intervention based on light/moderate aerobic exercise accompanied by meditative components, has improved aerobic capacity in older sedentary adults as well as exercise self-efficacy, quality of life and mood in patients with heart failure. Tai Chi can be practiced safely by elderly and deconditioned individuals; it does not require any particular equipment and it may be performed at any time and place. Since Tai Chi is usually taught in groups, and is safe even in high-risk patients, it has been successfully offered in community centers thus overcoming transportation barriers and limiting costs. All these characteristics indicate that Tai Chi may overcome multiple barriers to traditional CRP and could be proposed as an alternative intervention for patient unwilling to attend traditional CRPs. Our long-term goal is conduct a phase III randomized clinical trial (RCT) to determine the efficacy of Tai Chi in improving overall physical activity in patients with recent coronary events or procedures that are unable or unwilling to attend traditional CRPs. The objectives of this treatment development study are to define the content, optimal dose, feasibility and safety of a Tai Chi intervention in this new population and to optimize the design of the future RCT. Specifically, (aim 1) we will use a modified Delphi technique to develop a Tai Chi intervention tailored to the specific rehabilitative needs of patients with recent coronary events or procedures that are unable or unwilling to attend traditional CRPs. Next, (aim 2) we will define the appropriate dose of the intervention by comparing the feasibility, acceptability and safety of two doses of the Tai Chi intervention. 60 patients (30 per dose arm) will be randomized to a low dose of Tai Chi (the dose used in our previous studies with heart failure patients) or to a high dose matching current recommendations for the frequency and duration of exercise classes in current CRPs. We will obtain estimates of the effect of each dose on physical activity and on the proportion of patients achieving current recommendation for physical activity. Additional outcomes will be body weight, fitness, quality of life, exercise self-efficacy, mindfulness, perceived social suppor, depression and sleep. Measurements will be conducted at baseline, 3-, 6-, and 9- months after enrollment. Lastly, (aim 3) the investigative team will make the final adjustments to the Tai Chi intervention protocol based on findings from the dosing study and will finalize the design of the future RCT.